The present invention relates to an apparatus for recirculating highly viscous or semi-fluid lubricants that are used to lubricate various machine components of a mechanism. More specifically, the present invention relates to an apparatus for recirculating highly viscous or semi-fluid lubricants in batch fashion.
Two types of systems presently exist for lubricating machine components. The first is a total loss lubrication system (once through) where fresh clean lubricant is continuously applied to the machine components of the system. The second is a recirculating system where a liquid lubricant is initially applied to the machine components of a system at its use points. After the lubricant contacts the components, spent lubricant is collected in a sump. The spent lubricant is then sent through a filter to remove the bulk of impurities before it is recirculated for reapplication to the system use points. Current recirculating systems usually operate in a continuous or near-continuous fashion and thus low to moderately high viscosity fluids are usually recirculated. Common machine components requiring lubrication include open and semi-open gear drives, bushings, and plain bearings, rolling element bearings, slideways and rams.
It is acknowledged in the art that the ideal method of lubricating most, if not all, types of machine components is through the use of a recirculating oil system. However, overall design and/or application restrictions often prohibit the practical incorporation of such a system of lubrication. As a result, at present, where it is impractical to install a recirculating oil system, total loss lubrication systems are commonly installed.
Because of various design and application restrictions, many industrial machines employ a total loss lubrication system. In mechanisms which are subjected to extremely high shear forces and temperatures, lower viscosity fluids may not adequately protect the rams, bushings, open and semi-open gear drives, plain bearings, rolling element bearings, slideways, and other components of the mechanism because lower-viscosity lubricants can break down and provide minimal or no protection for the machine components. Highly viscous, semi-fluid lubricants such as greases or high viscosity base oil gels are used because they are more resistant to breakdown. However, because of the difficulties in recirculating these higher viscosity lubricants, the components are commonly lubricated by a total loss system.
For example, one industrial machine that suffers from these restrictions is the cover lifting and rotating mechanism of an electric arc furnace. The cover lifting and rotating mechanism, contained in a steel mill furnace and used to supply continuous metal casters, may employ rams, bushings and other components that require highly viscous or semi-fluid lubricants in order to ensure safe and reliable operation.
As systems requiring highly viscous or semi-fluid lubricants use the total loss lubrication system, fresh clean lubricant must be continuously applied to their components at a desired rate. This makes these systems much more costly to operate than recirculating oil systems, from both an initial and spent lubricant disposal cost basis. In addition, total loss lubrication can waste non-renewable resources such as mineral oil based lubricants, and can be environmentally undesirable. Thus, a recirculating system for semi-fluid lubricants would be less costly to operate and environmentally more desirable.